(1) Field of the Invention.
The invention disclosed herein is an automatic tree stem cutting apparatus which is designed to rapidly process substantially tree length stems into logs, poles or other segments for further processing in pole mills, sawmills, plywood plants and the like. This invention relates to a high-speed continuous-feed log bucking system; more particularly, the invention disclosed herein relates to an apparatus for precise dissection of tree trunk stems continuously traveling lineally. The invention described herein essentially executes a cutting pattern on a trunk stem “on the fly”, by receiving input or cut-positioning directives concerning the unique physical characteristics of the workpiece stem traveling lengthwise atop the lineal conveyor(s), the saw carrier traveling in like direction obliquely and parallel above the stem until the correct cut point and matching speed is realized, bisecting the correct cut site while the stem remains traveling.
(2) Description of the Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98.
Trees grow in an essentially infinite variety of dimensions and configurations. There is great diversity in physical characteristics such as (for example) the longitudinal lengths and diameters of tree trunks, limb numbers and positioning, trunk curvature and bifurcation, and the presence of knots, depressions or other irregularities. Processing a tree from harvestable timber to finished end product often includes several steps requiring a high degree of precision, accompanied by great flexibility due to the variation and diversity of the characteristics of each workpiece stem. After the tree is felled, many of the smaller limbs are removed, and the remaining trunk stem is transported (along with other trunk stems) to an area to be “bucked”. The modern “bucking” process involves analyzing each individual unique stem for the optimum manner of segmenting it to maximize the yield of wood product(s) desired.
Analysis of each unique stem, to determine the best place(s) to cut to optimize the yield, may be accomplished by manual scrutiny and figuring. However, technological advances, especially in the laser and optical sciences, facilitate mechanized and computerized scanning and analysis that is usually faster and more accurate. Such scanning devices typically fall into two categories: lineal scanning down the entire length of the stem, or transverse scanning by a plurality of scanners at select points along the stem. Historically, lineal scanning has generally been slower than transverse scanning, because it usually took longer for a lineal conveyor to move the stem past the lineal scanner; however, lineal scanning has usually been more accurate, and it requires less capital investment because it may be accomplished with only one scanner rather than a plurality. On the other hand, since the transverse scanning distance is so short (essentially the diameter of the trunk), it is usually the quickest scanning method, but the accuracy is never quite comparable to a linear scanner and usually requires several scanners having scanning fields that overlap to produce essentially one combined scanning field substantially the length of the stem.
As with stem scanning techniques, there are two well known methods of moving stems into position to be cut, and these methods are known as lineal flow and transverse flow. With lineal conveyors, each stem travels longitudinally (lengthwise) into a position where it is cut transversely (cross-sectioned) by an otherwise immobile saw or other cutting device; usually there is an endstop dowstream of the saw, which stops the travel of the stem (at the desired length from the saw) long enough for the saw to cut it at the desired length. With the transverse flow method of conveyance (such as a slasher deck or log trimmer system), each stem is moved sideways up to a plurality of saws or cutting devices. The saw(s) of most transverse flow cutting systems do not move toward or away from the stem; the conveyor usually moves the stem to and through the saw(s), although the saw(s) may move along the longitudinal length of the stem to a position for a cut point within the range of its particular longitudinal field. However, physical space limitations make it difficult or impossible to position saws close enough to make several precise adjacent cuts; moreover, positioning enough saws at intervals along the stem to make all of the precise desired cuts essentially simultaneously would require the purchase and maintenance of many more saws than is generally economically feasible to utilize in this industry.
Both lineal and transverse conveyors experience variable speeds during use. Such variations generally depend upon a variety of circumstances effecting the conveyance such as the weight and size of the stem(s) being conveyed, the timing sequences needed to position the cutting apparatus for the desired cut(s), and the speed at which the stem can be conveyed away after being cut.
It is important in the sawing of stems that the cuts be made to maximize the quantity and quality of products yielded by each stem. These yields depend upon the length, diameter, configuration and quality of the stem. The best yield often requires cutting that takes into account the presence of curves, knots, defects and the like. The lineal method of bucking is generally better at maximizing the value and yield from the stem, especially if multiple saws can be synchronized to implement the precise pattern of unique cuts while the stem maintains its travel at acceptably high speeds. The transverse flow method is typically hampered in removing defects due to physical limitation of moving a multiplicity of saws closely enough together, or without employing a large number of cutting devices and repeated movements of the stem.
The following patents are arguably related to the patentability of the subject invention:
U.S. Pat. No.Issue Date1st Inventor6,158,318December 2000Neimela6,089,135July 2000Murray6,032,564May 2000Bowlin5,579,671December 1996Bowlin5,522,292June 1996Biagiotti5,243,889September 1993Wallis4,939,967July 1990Wallis4,640,160February 1987Hards4,616,542October 1986Hards4,468,993September 1984McCown, Et al4,391,170July 1983Boverman, Et al4,330,019May 1982Murphy, Et al4,204,798May 1980Warren, Et al4,085,638April 1978Fifer3,937,114February 1976Joensson, Et al3,919,906November 1975Law3,892,153July 1975Kato3,808,928May 1974Plegat3,178,974April 1965Roess
U.S. Pat. No. 4,616,542 issued to Hards discloses a lineal bucksaw system for cutting a log while it is traveling lengthwise. This patented bucksaw apparatus includes at least one clamp for gripping the log and lifting it upward toward the saw blade moving downward from directly above it; combined downward movement of the saw blade and upward movement of the clamped log causes the saw blade to bisect the log. Such upward lifting is necessary whenever saw blade motion is directly downward on a horizontal workpiece such as a log. As the saw blade cross-sections the top portion of the log, the log's inherent horizontal support is being severed, and gravity causes the adjacent sectioned portions of the log to fall downward and inward toward the blade; as the saw blade cuts deeper into the log, both of the new log-segment ends being created by the cutting push together separated only by the saw blade, often binding the saw blade between them. The clamp is critical to the Hards bucking system.
U.S. Pat. No. 4,640,160 issued to Hards generally discloses a log bucking system for implementing log cutting as the log continues its lineal travel. The apparatus is constructed and operated in accordance with the teachings of the aforementioned U.S. Pat. No. 4,616,542. ('160 Patent, column 2 lines 33 to 39.)
Also known are so-called “shifting” saw systems. In these types of systems, a stem is stopped in its lineal travel, one or more saws are shifted to defined distances from the established “zero” end (beginning measuring point), then the multiple saws simultaneously cut the stem into logs and retract bforee the log can again begin its forward travel.
Many of the aforementioned patents disclose technology in fields other than the timber cutting field. These patents are included out of an abundance of caution, without any admission that they are in technological fields analogous to the present invention. Moreover, the present invention is distinguishable from most of those patents, which often involve making uniform cuts on a workpiece (such as pipe) having uniform dimensions, resulting in segments of uniform length or other uniform characteristics.